Recombinant Sheep Pregnancy-associated glycoprotein 59
Description
Table 1: Analytical Systems for PAG Quantification
Radioimmunoassays (RIA) demonstrate earlier detection capabilities compared to ELISA, with RIA-706 achieving 90.1% sensitivity in Sarda ewes by gestational day 18 . Cross-reactive bovine ELISA systems show 93.5% sensitivity in sheep but require later sampling (≥33 days) .
Table 2: Comparative PAG Profiles in Ruminants
| Parameter | Sheep | Cattle | Buffalo |
|---|---|---|---|
| First Detection | Day 18-22 | Day 15-22 | Day 25 |
| Peak Concentration | 60 days & prepartum | Exponential rise | Day 105 plateau |
| Postpartum Half-life | 4.5-6.9 days | 9 days | 8.5 days |
Sheep exhibit biphasic PAG surges with initial peaks at 60 days gestation followed by secondary prepartum elevations . This contrasts with cattle's continuous exponential rise and buffaloes' mid-gestation plateaus .
Clinical Applications
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Early pregnancy diagnosis: RIA systems achieve 90-99% accuracy by day 28 in sheep
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Fetal viability monitoring: Strong correlation between PAG levels and trophoblast health
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Litter size prediction: Multiple pregnancies show 23-35% higher PAG concentrations than singletons
Metabolomic analyses reveal concomitant changes in acetic acid (↑147%), urea (↑89%), and L-arginine (↓62%) levels with PAG elevations during ovine pregnancy .
Knowledge Gaps and Future Directions
While recombinant PAG production remains undocumented in sheep, goat studies demonstrate successful purification of native 59 kDa PAGs through chromatographic techniques . Current limitations include:
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Lack of isoform-specific assays for functional studies
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Undefined glycosylation patterns affecting immunodetection
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Limited data on recombinant protein stability and bioactivity
